Producing high-quantity and high-quality recombinant adeno-associated virus by low-cis triple transfection.

Recombinant adeno-associated virus (rAAV)-based gene therapy is entering clinical and commercial stages at an unprecedented pace. Triple transfection of HEK293 cells is currently the most widely used platform for rAAV manufacturing. Here, we develop low-cis triple transfection that decreases transgene plasmid use by 10- to 100-fold and overcomes several major limitations associated with standard triple transfection. This new method improves packaging of yield-inhibiting transgenes by up to 10-fold, and generates rAAV batches with reduced plasmid backbone contamination that otherwise cannot be eliminated in downstream processing. When tested in mice and compared with rAAV produced by standard triple transfection, low-cis rAAV shows comparable or superior potency and results in diminished plasmid backbone DNA and RNA persistence in tissue. Mechanistically, low-cis triple transfection relies on the extensive replication of transgene cassette (i.e., inverted terminal repeat-flanked vector DNA) in HEK293 cells during production phase. This cost-effective method can be easily implemented and is widely applicable to producing rAAV of high quantity, purity, and potency.

Modulation of gut microbiota by crude mulberry polysaccharide attenuates knee osteoarthritis progression in rats.

Mulberry (Morus alba L.), a kind of common fruits widely cultivated worldwide, has been proven various biological activities. However, its potential role in the progression of knee osteoarthritis (KOA) remains unclear. This study aims to investigate the potential protective effects of crude polysaccharide extracted from mulberry fruit, referred to as a complex blend of polysaccharides and other unidentified extracted impurities, on KOA progression. The KOA rats were established by injection of 1 mg sodium monoiodoacetate into knee, and administrated with crude mulberry polysaccharide (Mup) by gastric gavage for 4 weeks. Furthermore, intestinal bacteria clearance assay (IBCA) and fecal microbiota transplantation were conducted for the evaluation of the effect of gut microbiota (GM) on KOA. Our findings demonstrated that Mup, particularly at a dosage of 200 mg/kg, effectively improved abnormal gait patterns, reduced the level of inflammation, mitigated subchondral bone loss, restored compromised joint surfaces, alleviated cartilage destruction, and positively modulated the dysregulated profile of GM in KOA rats. Moreover, IBCA compromised the protective effects of Mup, while transplantation of fecal bacteria from Mup-treated rats facilitated KOA recovery. Collectively, our study suggested that Mup had the potential to ameliorate the progression of KOA, potentially through its modulation of GM profile.

Non-canonical amino acid incorporation into AAV5 capsid enhances lung transduction in mice.

Gene therapy using recombinant adeno-associated virus (rAAV) relies on safe, efficient, and precise in vivo gene delivery that is largely dependent on the AAV capsid. The proteinaceous capsid is highly amenable to engineering using a variety of approaches, and most resulting capsids carry substitutions or insertions comprised of natural amino acids. Here, we incorporated a non-canonical amino acid (ncAA), Nε-2-azideoethyloxycarbonyl-L-lysine (also known as NAEK), into the AAV5 capsid using genetic code expansion, and serendipitously found that several NAEK-AAV5 vectors transduced various cell lines more efficiently than the parental rAAV5. Furthermore, one NAEK-AAV5 vector showed lung-specific transduction enhancement following systemic or intranasal delivery in mice. Structural modeling suggests that the long side chain of NAEK may impact on the 3-fold protrusion on the capsid surface that plays a key role in tropism, thereby modulating vector transduction. Recent advances in genetic code expansion have generated synthetic proteins carrying an increasing number of ncAAs that possess diverse biological properties. Our study suggests that ncAA incorporation into the AAV capsid may confer novel vector properties, opening a new and complementary avenue to gene therapy vector discovery.

Complete genetic characterization of carbapenem-resistant Acinetobacter johnsonii, co-producing NDM-1, OXA-58, and PER-1 in a patient source.

The emergence of carbapenemase-producing Acinetobacter spp. has been widely reported and become a global threat. However, carbapenem-resistant A. johnsonii strains are relatively rare and without comprehensive genetic structure analysis, especially for isolates collected from human specimen. Here, one A. johnsonii AYTCM strain, co-producing NDM-1, OXA-58, and PER-1 enzymes, was isolated from sputum in China in 2018. Antimicrobial susceptibility testing showed that it was resistant to meropenem, imipenem, ceftazidime, ciprofloxacin, and cefoperazone/sulbactam. Whole-genome sequencing and bioinformatic analysis revealed that it possessed 11 plasmids. bla OXA-58 and bla PER-1 genes were located in the pAYTCM-1 plasmid. Especially, a complex class 1 integron consisted of a 5' conserved segment (5' CS) and 3' CS, which was found to carry sul1, arr-3, qnrVC6, and bla PER-1 cassettes. Moreover, the bla NDM-1 gene was located in 41,087 conjugative plasmids and was quite stable even after 70 passages under antibiotics-free conditions. In addition, six prophage regions were identified. Tracking of closely related plasmids in the public database showed that pAYTCM-1 was similar to pXBB1-9, pOXA23_010062, pOXA58_010030, and pAcsw19-2 plasmids, which were collected from the strains of sewage in China. Concerning the pAYTCM-3 plasmids, results showed that strains were collected from different sources and their hosts were isolated from various countries, such as China, USA, Japan, Brazil, and Mexico, suggesting that a wide spread occurred all over the world. In conclusion, early surveillance is warranted to avoid the extensive spread of this high-risk clone in the healthcare setting.

Emergence of IS26-mediated pLVPK-like virulence and NDM-1 conjugative fusion plasmid in hypervirulent carbapenem-resistant Klebsiella pneumoniae.

Hypervirulent carbapenem-resistant Klebsiella pneumoniae (hv-CRKP) has been widely reported and poses a global threat. However, the comprehensive genetic structure of ST11-KL64 hv-CRKP and the possible evolutionary mechanisms from a genetic structure perspective of this high-risk clone remain unclear. Here, a blaKPC-2-blaNDM-1-positive ST11-KL64 hv-CRKP isolate was obtained from a human bloodstream infection (BSI). Whole-genome sequencing and bioinformatics analyses revealed that it contained a fusion plasmid, pKPTCM2-1. pKPTCM2-1 is a conjugative plasmid composed of an oriT-positive pLVPK-like virulence plasmid and a type IV secretion system-produced blaNDM-1-bearing IncX3 plasmid mediated by IS26-based co-integration. This progress generated 8-bp target site duplications (TGAAAACC) on both sides. The fusion plasmid possessed self-transferability and could be transferred to blaKPC-2-harboring ST11-KL64 CRKP to form the ST11-KL64 hv-CRKP clone. The pLVPK-like-positive ST11-KL64 strain exhibited virulence levels similar to those of the typical hypervirulent K. pneumoniae NTUH-2044. The mutation, Tet(A) (A276S), which was believed to lead to tigecycline resistance was observed. Overall, this high-risk clone has emerged as a tremendous threat in fatal BSIs and thus, targeted surveillance is an urgent need to contain the hv-CRKP clones.

Sanziguben polysaccharides improve diabetic nephropathy in mice by regulating gut microbiota to inhibit the TLR4/NF-κB/NLRP3 signalling pathway.

CONTEXT: Sanziguben (SZGB) is an empirical prescription used in traditional Chinese medicine to treat diabetic nephropathy (DN). As an abundant and primarily effective component of SZGB, Sanziguben polysaccharides (SZP) can be digested by flora to generate biological activity. OBJECTIVE: Our study aimed to clarify the potential mechanism of SZP in improving chronic DN. MATERIALS AND METHODS: Male db/db mice were randomized into DN, SZP (500 mg/kg) and metformin (MET, 300 mg/kg) groups. Wild-type littermates served as the normal control (NC) group. The drug was orally administered for 8 weeks. Enzyme-linked immunosorbent assay was used to detect the inflammatory factors. Proteins related to inflammation were evaluated using western blotting and immunohistochemical examination. Gut microbiota was analysed using 16S rRNA sequencing. RESULTS: SZP significantly reduced 24 h urine albumin (p < 0.05) of DN mice. Compared to DN group, SZP significantly decreased the homeostasis model assessment of insulin resistance index, serum creatinine and blood urea nitrogen levels (20.27 ± 3.50 vs. 33.64 ± 4.85, 19.22 ± 3.77 vs. 32.52 ± 3.05 µmol/L, 13.23 ± 1.42 vs. 16.27 ± 0.77 mmol/L, respectively), and mitigated renal damage. SZP also regulated gut microbiota and decreased the abundance of Gram-negative bacteria (Proteobacteria, Klebsiella and Escherichia-Shigella). Subsequently, SZP reduced lipopolysaccharides levels (1.06- to 1.93-fold) of DN mice. Furthermore, SZP inhibited the expression levels of TLR4, phospho-NF-κB p65, NLRP3 proteins and interleukin (IL)-18 and IL-1ß. CONCLUSIONS: These results demonstrated that SZP improved intestinal flora disorder and inhibited the TLR4/NF-κB/NLRP3 pathway to alleviate DN.

Compatibility between cold-natured medicine CP and hot-natured medicine AZ synergistically mitigates colitis mice through attenuating inflammation and restoring gut barrier.

ETHNOPHARMACOLOGICAL RELEVANCE: Ulcerative colitis (UC) is a nonspecific intestinal inflammation with complex pathogenesis. Traditional Chinese Medicine (TCM) formula consists of several TCM herbs following the principle of herbal property and compatibility. Our previous studies found that Huanglian Ganjiang decoction (HGD) exhibited anti-colitis capacity and the compatibility between hot-natured medicine and cold-natured medicine was main compatibility. However, the association between compatibility mechanism of HGD and its anti-colitis effect has not been fully illustrated yet. AIM OF STUDY: Here, we would explore whether cold-natured medicine Coptis chinensis Franch. plus Phellodendron chinense C.K.Schneid. (CP) and hot-natured medicine Angelica sinensis (Oliv.) Diels plus Zingiber officinale Roscoe (AZ) in HGD respectively produce different impacts on UC, and exert synergistic effect on UC together. MATERIALS AND METHODS: UPLC/MS-MS was used to qualitatively analyze chemical profiles of CP, AZ and CPAZ extracts. CPAZ-UC target network was constructed using network pharmacology. Colitis mice was induced by 3% DSS for 7 days and treated with CP, AZ and CPAZ for another 7 days. The levels of multiple cytokines and proportions of innate and adaptive immune cells were determined to assess inflammatory profiles. The leakage of FITC-dextran, expressions of tight junction proteins were detected for evaluation of gut barrier function. RESULTS: CP, AZ and CPAZ could improve symptoms of colitis mice. CP showed superiority in reducing proportions of pro-inflammatory immune cells M1 cells, neutrophils, Th1 and Th17 cells, and levels of pro-inflammatory cytokines IFN-γ, IL-6, IL-10, TNF-α. In the contrast, AZ had advantage of elevating ratios of anti-inflammatory immune cells M2 and Treg cells as well as the production of anti-inflammatory cytokines IL-10 and TGF-ß. In addition, CP and AZ synergistically regulated M1/M2 macrophage polarization and the following IL-6, IL-10, TNF-α, IFN-γ production, thereby restoring intestinal mucosal barrier. CONCLUSION: Taken together, our study first demonstrated that cold-natured medicine CP and hot-natured medicine AZ took on different functions in treatment of colitis mice. Meanwhile, they exhibited synergistic effect on the alleviation of intestinal inflammation and reinforcement of gut barrier function and integrity.

Cyclovirobuxine D Brain-Targeted Liposomes Improve Cerebral Ischemia-Reperfusion Injury via Anti-Oxidant Stress and Activating Autophagy.

One of the main issues faced by nervous system diseases is that drugs are difficult to enter the brain. The previous study suggested that Cyclovirobuxine D (CVBD) encapsulated in Angiopep-conjugated Polysorbate 80-Coated Liposomes showed a better brain targeting by intranasal administration. Therefore, this study concentrated on the protection and mechanism of CVBD brain-targeted liposomes in treating CIRI. Middle cerebral artery occlusion-reperfusion induced CIRI model rats to explore the protective effect of CVBD brain-targeted liposome on CIRI. Moreover, the protective effect of CVBD liposomes on OGD/R-injured HT22 cells was examined by cell fusion degree, cell proliferation curve and cell viability. OGD/R-injured HT22 cell was infected by mRFP-GFP-LC3 adenovirus. The autophagosome and autophagy flow were observed by laser confocal microscopy, and autophagy-related protein expressions were analyzed by Western blot. The classic autophagy inhibitor, chloroquine, was used to explore the autophagy-regulatedmechanism of CVBD brain-targeted liposomes in treating CIRI. CVBD liposomes increased cell viability and decreased ROS level, improved oxidative stress protein expressions and activated autophagy in vitro. Furthermore, CVBD liposomes reversed the decrease of cell viability, increase of ROS level, and reduction of protein expressions associated with anti-oxidative stress and autophagy induced by chloroquine. Collectively, CVBD liposomes inhibited CIRI via regulating oxidative stress and enhancing autophagy level in vivo and in vitro.

AAV-delivered suppressor tRNA overcomes a nonsense mutation in mice.

Gene therapy is a potentially curative medicine for many currently untreatable diseases, and recombinant adeno-associated virus (rAAV) is the most successful gene delivery vehicle for in vivo applications1-3. However, rAAV-based gene therapy suffers from several limitations, such as constrained DNA cargo size and toxicities caused by non-physiological expression of a transgene4-6. Here we show that rAAV delivery of a suppressor tRNA (rAAV.sup-tRNA) safely and efficiently rescued a genetic disease in a mouse model carrying a nonsense mutation, and effects lasted for more than 6 months after a single treatment. Mechanistically, this was achieved through a synergistic effect of premature stop codon readthrough and inhibition of nonsense-mediated mRNA decay. rAAV.sup-tRNA had a limited effect on global readthrough at normal stop codons and did not perturb endogenous tRNA homeostasis, as determined by ribosome profiling and tRNA sequencing, respectively. By optimizing the AAV capsid and the route of administration, therapeutic efficacy in various target tissues was achieved, including liver, heart, skeletal muscle and brain. This study demonstrates the feasibility of developing a toolbox of AAV-delivered nonsense suppressor tRNAs operating on premature termination codons (AAV-NoSTOP) to rescue pathogenic nonsense mutations and restore gene function under endogenous regulation. As nonsense mutations account for 11% of pathogenic mutations, AAV-NoSTOP can benefit a large number of patients. AAV-NoSTOP obviates the need to deliver a full-length protein-coding gene that may exceed the rAAV packaging limit, elicit adverse immune responses or cause transgene-related toxicities. It therefore represents a valuable addition to gene therapeutics.

Structural characterization of a novel human adeno-associated virus capsid with neurotropic properties.

Recombinant adeno-associated viruses (rAAVs) are currently considered the safest and most reliable gene delivery vehicles for human gene therapy. Three serotype capsids, AAV1, AAV2, and AAV9, have been approved for commercial use in patients, but they may not be suitable for all therapeutic contexts. Here, we describe a novel capsid identified in a human clinical sample by high-throughput, long-read sequencing. The capsid, which we have named AAVv66, shares high sequence similarity with AAV2. We demonstrate that compared to AAV2, AAVv66 exhibits enhanced production yields, virion stability, and CNS transduction. Unique structural properties of AAVv66 visualized by cryo-EM at 2.5-Å resolution, suggest that critical residues at the three-fold protrusion and at the interface of the five-fold axis of symmetry likely contribute to the beneficial characteristics of AAVv66. Our findings underscore the potential of AAVv66 as a gene therapy vector.

Gene Delivery to Nonhuman Primate Preimplantation Embryos Using Recombinant Adeno-Associated Virus.

Delivery of genome editing tools to mammalian zygotes has revolutionized animal modeling. However, the mechanical delivery method to introduce genes and proteins to zygotes remains a challenge for some animal species that are important in biomedical research. Here, an approach to achieve gene delivery and genome editing in nonhuman primate embryos is presented by infecting zygotes with recombinant adeno-associated viruses (rAAVs). Together with previous reports from the authors of this paper and others, this approach is potentially applicable to a broad range of mammals. In addition to genome editing and animal modeling, this rAAV-based method can facilitate gene function studies in early-stage embryos.

Adeno-Associated Virus Neutralizing Antibodies in Large Animals and Their Impact on Brain Intraparenchymal Gene Transfer.

Pre-existing neutralizing antibody (NAb) against adeno-associated virus (AAV) commonly found in primates is a major host barrier that can severely compromise in vivo gene transfer by AAV vectors. To achieve proof-of-concept success in clinical development of recombinant AAV (rAAV)-based in vivo gene therapy, it is crucial to consider the potential interference of NAb and to enroll serologically compatible study subjects. In this study, we report a large AAV NAb dataset comprising multiple large animal species and AAV serotypes and compare two NAb assays based on in vitro or in vivo transduction inhibition, respectively. Together with previously published AAV seroepidemiology studies, these data can serve as a reference for selecting suitable serotypes, study subjects of large animal species, and potentially human patients for rAAV treatment. In addition, we modeled the intrathalamus rAAV9 delivery in the presence of circulating anti-AAV9 NAb generated by either pre-immunization or passive transfer of NAb-positive large animal serum to mice. The data showed that circulating NAb may not be the sole determinant to inhibit brain transduction. Other aspects of pre-existing AAV immunity following natural infection or rAAV administration may be further studied to establish a more accurate inclusion criterion for clinical studies employing intraparenchymal rAAV9 injections.

Cas9-mediated allelic exchange repairs compound heterozygous recessive mutations in mice.

We report a genome-editing strategy to correct compound heterozygous mutations, a common genotype in patients with recessive genetic disorders. Adeno-associated viral vector delivery of Cas9 and guide RNA induces allelic exchange and rescues the disease phenotype in mouse models of hereditary tyrosinemia type I and mucopolysaccharidosis type I. This approach recombines non-mutated genetic information present in two heterozygous alleles into one functional allele without using donor DNA templates.

A Rationally Engineered Capsid Variant of AAV9 for Systemic CNS-Directed and Peripheral Tissue-Detargeted Gene Delivery in Neonates.

Adeno-associated virus (AAV) has provided the gene therapy field with the most powerful in vivo gene delivery vector to realize safe, efficacious, and sustainable therapeutic gene expression. Because many clinically relevant properties of AAV-based vectors are governed by the capsid, much research effort has been devoted to the development of AAV capsids for desired features. Here, we combine AAV capsid discovery from nature and rational engineering to report an AAV9 capsid variant, designated as AAV9.HR, which retains AAV9's capability to traverse the blood-brain barrier and transduce neurons. This variant shows reduced transduction in peripheral tissues when delivered through intravascular (IV) injection into neonatal mice. Therefore, when IV AAV delivery is used to treat CNS diseases, AAV9.HR has the advantage of mitigating potential off-target effects in peripheral tissues compared to AAV9. We also demonstrate that AAV9.HR is suitable for peripheral tissue-detargeted CNS-directed gene therapy in a mouse model of a fatal pediatric leukodystrophy. In light of recent success with profiling diversified natural AAV capsid repertoires and the understanding of AAV capsid sequence-structure-function relationship, such a combinatory approach to AAV capsid development is expected to further improve vector targeting and expand the vector toolbox for therapeutic gene delivery.